In recent years, the use of mobile devices has increased in popularity among consumers. For example, mobile devices such as personal digital assistants (PDAs), smartphones, cellular phones, tablet computers, laptop computers, digital cameras, and portable music or video players are being widely used by consumers due to their portability. To ensure their portability, these devices typically include a battery to allow a user to operate the devices without a continuous connection to a power adaptor.
In general, mobile devices are equipped with a rechargeable battery for supplying electrical power. Rechargeable batteries are typically charged via a physical electrical line to a power source. As an alternative to charging via a physical electrical connection, some mobile devices have allowed the batteries to be charged wirelessly.
In conventional wireless charging methods, a mobile device communicates power control information to a base station to control the power transfer from the base station. For example, in a wireless charging system using an out-of-band signaling approach, power control information is communicated in a channel that is different from the channel used for power transfer. However, this method requires the use of additional resources for the communication channel, with additional cost and complexity.
An in-band signaling approach allows the power control information to be communicated via the same channel used for power transfer. In this method, however, the information transmission from a mobile device may adversely affect the power transmission since both the information and the power are transmitted on the same channel. Further, conventional wireless charging methods typically allow charging between a single device and a base station. As such, the charging of multiple devices may require multiple base stations.
Thus, there is a need for a wireless charging system and method that can reliably and efficiently control the power transmitted to mobile devices without requiring multiple base stations.